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  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      var arr = [24, 22, 21, 20, 19];
      // 求里边所有数字的平均值

      // 求和
      var sum = 0;
      for (var i = 0; i < arr.length; i++) {
        sum += arr[i];
      }
      // 取平均
      console.log(sum / arr.length);
    </script>
  </body>
</html>
